Nondusting,high temperature dryer

ABSTRACT

Apparatus and method for low dust level drying of material in continuous drying apparatus of the type utilizing a plurality of vertically superimposed, rotating trays to convey the material through the dryer. Billowing of the material, and hence dust formation, is retarded by delivering the material to the dryer, and thereafter transferring it between vertically adjacent trays, through inclined chutes. Upon each revolution of the trays, wiper arms guide the material on each tray over the edge of the tray, while other wiper arms and leveler arms distribute the material discharged on to each tray from the next higher tray over the surface of the tray. All side and both end walls of the dryer housing are thermally insulated to maintain high drying temperatures, and the skeletal support structure, as well as the trays and end walls of the housing, are constructed to expand or contract laterally in response to temperature changes within the housing, thus allowing uninterrupted operation of the dryer over a wide range of temperatures, including highly elevated temperatures.

United States Patent Weisselberg et al.

[54] NONDUSTING, HIGH TEMPERATURE DRYER [72] Inventors: Edward B.Weisselberg, Old Tappan; George M. Worden, Sr., Park Ridge; William F.Lamp, Closter;

Alexander M. Lane, Allendale, all of NJ.

[73] Assignee: Wyssmont Company, Inc., Fort Lee,

[22] Filed: Feb. 5, 1970 [21] Appl. No.: 8,985

[451 Aug. 8, 1972 699 1863 Great Britain ..34/173 PrimaryExaminer-Frederick L. Matteson Assistant Examiner-Harry B. RarneyAttorney-Brumbaugh, Graves, Donohue & Raymond ABSTRACT Apparatus andmethod for low dust level drying of material in continuous dryingapparatus of the type utilizing a plurality of vertically superimposed,rotating trays to convey the material through the dryer. Billowing ofthe material, and hence dust formation, is retarded by delivering thematerial to the dryer, and thereafter transferring it between verticallyadjacent .trays, through inclined chutes. Upon each revolution of thetrays, wiper arms guide the material on each tray over the edge of thetray, while other wiper arms and leveler arms distribute the materialdischarged on to each tray from the next higher tray over the surface ofthe tray. All side and both end walls of the dryer housing are thermallyinsulated to maintain high drying temperatures, and the skeletal supportstructure, as well as the trays and end walls of the housing, areconstructed to expand or contract laterally in response to temperaturechanges within the housing, thus allowing uninterrupted operation of thedryer over a wide range of temperatures, including highly elevatedtemperatures.

12 Claims, 13 Drawing figures FIG. 34

FIG. 3B

P'A'TENTEDAus 8 m2 3,681. 855

sum 2 or 7 I GEORGE M. WORDEN. SR, 1 raza'mwmfi their 4770 NEYSPATENTEBAW; 81972 3,681. 855

sum 3 or 7 INVENTORS GEORGE M. WORDEN, SR,

WILLIAM F LAMP &

BY ALEXANDER M. LANE BAAAWLMSAI M004 EDWARD B. WEISSELBERG,

PASTENTFUAIJQ 8 I972 3,681,855

INVENTORS WILLIAM F. LAMP 8 Y ALEXAANDER LANE 2% W ba i g l I their 47 70 IVEYS EDWARD a WEISSELBERG, GEORGE M. wonosu, sR.,

PATENTEGAUQ 8l972 855 sum 5 0F 7 EDWARD B.WEISSELB GEORGE mwonogu,

W IAM AMP A AND M. LA

SHEET 6 BF 7 3 U 1' 8 \UIV $m U mmwmmrlz Iv U 3% wwwn |I IU 00m I Iv .v9% E \v Q L Q 5 w\\ 08m v INVENTORS EDWARD awassELaERe, GEORGE M.wonozrmsa, WILLIAM E LAMP a PATENTEDI B 819?? 3.681. 855

sum 7 or INVENTORS EDwARD a. WEISSELBERG, GEORGE M. WORDEN, sR., WILLIAME LAMP a ALEXANDER M. LANE MAM! M 7) 0M W4 fineir {rm NEYS NONDUSTING,HIGH TEMPERATURE DRYER BACKGROUND OF THE INVENTION method for processingmaterial in rotary tray dryers while retarding billowing of thematerial, and hence dust creation, as it is advanced through the dryer.Additionally, the invention is directed to continuous dryers of thistype in which the dryer housing is fully insulated, and the dryerskeletal structure and material carrying surfaces constructed to allowthermally induced expansion or contraction thereof, to facilitateuninterrupted operation of the dryer at elevated temperatures.

- material over the laterally outeredges of the trays and 1 intotheupper ends of the inclined chutes, while additional wiper arms andleveler arms associated with each tray distribute the materialtransferred to the tray from the next highest tray evenly over thesurface of the tray. Thus, the transfer of the material through thedryer is very gentle, resulting in negligible breakage, minimumformation of fines and minimum adhesion of the material to the trays orto the transfer arms and chutes.

As the material advances from tray to tray in the dryer, the lateralposition of the material on the trays is alternated; that is to say, thematerial occupying the laterally outer portion of one tray, upon beingtransferred to the next lowest tray, is directed' to and spread over thelaterally inner portion of the lower tray. Conversely, the portion ofthe material that occupied the laterally inner portion of the highertray is moved to the laterally outer portion of the lower tray. Allsurfaces of Continuous rotary y dryers 0f the kind referred to thematerial are thus sought to be uniformly exposed to are known and, infact, have found wide acceptance in many industries. Such dryers aremanufactured under the trademark TURBO-Dryer by the Wyssmont Company,Inc., 1470 Bergen Boulevard, Fort Lee, N.J., the assignee of the presentapplication. The Wyssmont dryers generally produce a finished product ofhigh quality and uniformity even where such diverse materials ascrystals, powders, pellets, gels and slurries are processed through thedryers and where both high and low drying rates or material outputs arerequired.

It is desirable in certain applications, however, and in particularwhere finely divided or fragile materials are to be dried, that specialprovisions be made for minimizing billowing or breakage of the materialas it is conveyed through the dryers so as to retard dust formation.High dust levels within a dryer sometimes lead to operationaldifficulties, such as explosion hazards and clogging of the dryer andits associated equipment, which result in reduced drying efliciency andincreased costs. Moreover, by keeping dust levels within the dryer at aminimum, the need for elaborate dust collection and material returnequipment at the exit end of the dryer and, where the drying medium isrecirculated, the need for gas cleaning and process equipment can besignificantly reduced and, in some instances, entirely eliminated.

It is important also that continuous operation of the dryer at elevatedtemperatures be possible without interruption due to warping ordistortion of the dryer trays or supporting framework caused bydifferences in temperature between the interior and exterior of thedryer or by temperature variations within the dryer itself. Accordingly,apparatus is needed which will allow for thermally induced expansion andcontraction of critical dryer components to the extent necessary topermit operation of the dryer at the desired temperatures.

SUMMARY OF THE INVENTION between vertically adjacent trays. Uponrotation of the trays, wiper arms associated with each tray guide thethe drying medium.

High temperature operation of the dryer is made possible through acombination of insulating the dryer housing against heat loss andconstructing the load bearing skeletal structure and material carryingsurfaces of the dryer to permit lateral expansion and contraction ofthese components in response to temperature variations. Economies ofoperation are thus realized, as heat losses are kept at a low level, asignificant cost factor at high operating temperatures, and operationaldifficulties such as warping or jamming of the rotating trays areavoided. Moreover, greater flexibility of use of the dryer is achievedin that high temperatures can be maintained in the upper portions of thehousing to dry quickly and uniformly the materials delivered to thedryer, while the lower stages of the dryer can be used to cool the driedmaterial prior to its discharge from the dryer. Although large verticaltemperature gradients will exist in such instances, the insulationstructureand thermal expansion and contraction capabilities of the dryerpemiit continuous, uninterrupted operation of the dryer, with accuratetemperature control at the various drying and cooling stages.

The insulation structure for the dryer housing includes panel units thatextend between the vertical support columns spaced around the housingperiphery and individual, elongate insulator members positioned adjacentthe exterior side of each support column, thereby tending to maintainthe temperature of the support columns at or near the temperature of themore laterally inward portions of the housing. Insulated wall assembliesare located across both the upper and lower ends of the housing. Theupper wall assembly includes a hot roof and a cold roof, with the hotroof being suspended from the cold roof in a manner to be laterallymovable relative to the cold roof. Aligned openings provided in the hotand cold roofs to admit the various heating elements, drying mediumducts, material inlet assembly, etc., associated with the dryer to theinterior of the housing are oversized to an extent that expansion of thehot roof during operation of the dryer will not be impaired byengagement of the roof edges with the elements extending through theopenings.

Expansion joints are provided at both ends of the vertical columns sothat the columns may be displaced laterally as the housing expands orcontracts during operation. Expansion or contraction of the trays andbottom wall, which preferably are segmented, is provided for bysupporting the inner ends of the tray segments on a floating annularring and by slidably clamping the tray and bottom wall segments toradial support arms and an outer annular ring carried by the radialsupport arms.

. Preferably, slightly negative pressure is maintained within thehousing to provide an inward flow of air at any position on the dryerhousing where leakage of dust or drying medium from the housing might beexpected; Also, at the bearings joumaling the lower and upper ends ofthe tray shaft a pressurized flow of air is provided to prevent leakageof dust along the shaft and also to cool the bearings to temperaturessubstantially below those maintained within the dryer.

BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of theseand other aspects of the invention, as well as the objects andadvantages thereof, reference may be made to the following I detaileddescription and to the drawings, in which:

FIG. I is a side elevational view of a continuous rotary tray dryerconstructed in accordance with the present invention showing thelocations and orientations of the thermal expansion joints on thevertical support columns of the dryer housing;

FIG. 2 is a plan view taken along the line 2-2 of FIG. 1 and looking inthe direction of the arrows, with parts broken away for clarity ofillustration;

FIG. 3 shows the relationship of FIGS. 3A and 33',

FIGS. 3A and 3B are partial vertical sectional views of the upper andlower ends of the dryer taken along the line 3-3 of FIG. 2 and lookingin the direction of the arrows, with parts broken away for clarity;

FIG. 4 is an enlarged detail view of the material inlet chutearrangement of the invention taken along line 4-4 of FIG. 2 and lookingin the direction of the arrows; 1

FIG. 5' is a horizontal view taken along the line 5-5 of FIG. 4 andlooking in the direction of the arrows;

FIG. 6 is a horizontal sectional view taken along the line 6-6 of FIG.3B and looking in the direction of the arrows, with parts broken awayfor clarity of illustration;

FIG. 7 is a vertical sectional view taken along the line 7-7 of FIG. 6and looking in the direction of the arrows, with parts broken away fromclarity;

FIG. 8 is an enlarged detail view of the bottom wall and material outletchute arrangement of the invention taken along the line 8-8 of FIG. 3Band looking in the direction of the arrows;

FIG. 9 is an enlarged vertical sectional view taken along the line 99 ofFIG. 8 and looking in the direction of the arrows;

FIG. 10 is an enlarged vertical sectional view taken along the line 10l0of FIG. 8 and looking in the direction of the arrows; and

FIG 11 is an expanded schematic illustration of the circumferentiallocations of the material transfer chutes extending between verticallyadjacent trays and of the paths followed by the material as it advancesthrough the dryer.

DESCRIPTION OF AN EXEMPLARY EMBODIMENT In FIG. I, a continuous dryerconstructed in accordance with'the invention includes a generallyoctagon-shaped housing 20 having a skeletal support structure includingload-bearing colurrms 22 located at the apices of the housing sides, alower support frame 24 for the columns 22 and the drive equipment forthe dryer, and an upper support frame 26 for carrying the dryer heatingelements, intake and exhaust manifolds and-associated equipment and fortransmitting the 10a of this equipment to the support columns 22.

The columns 22 also support a plurality of panel units-28 which,together with an upper wall assembly 30 and a lower wall assembly 32,define an enclosed drying zone within the housing 20. As is more fullydisclosed hereinafter, girth members extend peripherally betweenadjacent columns and with the columns carry the panels 28 and wallassemblies 30 and 32.

A combustion fuel is delivered, as indicated by the arrows in FIGS. 1and 3A, through an intake manifold (not shown) and pipes 34 toadjustable metering devices 36 and chambers 38, where it is mixed withair delivered through pipes 40. The gas-air mixture is then burned ingenerally U-shaped heating elements 42, to raise and maintain thetemperature of the housing interior to the desired magnitude, and isexhausted, together with the combustion products produced in theelements 42, to an exhaust manifold 44 and thereafter to a stack (notshown) in communication with an exhaust duct 46 (see FIG. 1). As clearlyrepresented in FIG. 2, several heating elements 42 are spaced around theinner walls of the housing 20, with a corresponding number of meteringdevices 36 and chambers 38 being provided so that the heat generated byeach element 42 can be individually regulated. The exhaust manifold 44(see FIGS. 1 and 3A) takes the configuration of a partial annulus and isarranged to extend above each of the exhaust legs of the heatingelements 42 to facilitate connection with the elements, as, for example,by means of the ducts 48. If desired, the exhaust duct 46 and theconnector ducts 48 may be covered with insulating materialto reduce heatlosses and to keep temperatures at the upper end of the dryer frombecoming too high.

Instead of burning a gas-air mixture within the heating elements 42, ahigh temperature transfer liquid can be circulated through the elements.Also, steam, oil or electricity can be used as the heat source ratherthan a combustible gas.

A drying medium, such as air, inert gas or superheated steam, isadmitted into the housing 20 through intake ports (not shown) and iscirculated over the heating elements 42 and through the drying zonealong generally horizontal paths by a plurality of turbofans 50 (seeFIGS. 3 and 6) that are rotatably mounted centrally of the housing. Thedrying medium is thereafter exhausted from the dryer through a duct 52leading from the upper end of the housing. It is possible, of course, torecirculate the drying medium, or to pass it through a preheater beforefeeding it to the housing 20 to augment the heating capacity of theelements 42. Similarly, where a solvent is used to treat the materialfed to the dryer, the drying medium, which in this instance may be aninert gas, upon being exhausted from system. Also, further economies canbe realized by passing the effluents from either or both of the exhaustducts 46 and 52 through appropriate heat recovery systems. 7

The wet material to be processed in .the dryer is fed through an inletchute assembly 54 (see FIG. 3A) extending through the upper wallassembly 30 of the housing and is directed, as indicated by the arrows,onto the uppermost tray 56a of a vertical stack of superimposed trays.Each of the trays 56 is generally annular in plan and is supported forrotation within the housing in a generally horizontal plane by a cageassembly 58.

Turning briefly to FIGS. 3A, 3B and 6, the cage assembly 58 is formed bymultiplicity of circumferentially spaced stanchions 60 that are securedat either end to suitable frame structures 62 and 64. The upper frame 62connects with a hollow, rotatable shaft 66, while the bottom frame 64 isbolted to the rotatable upper part 63 of a thrust bearing assembly 65.The cage assembly 58, and hence the trays 56, is caused to rotate withinthe housing by a drive train including a driven gear 68 carried by theupper bearing part 63, a driver gear 70, a worm reducer 72 and a primemover 74. A second shaft 67, passing concentrically through the thrustbearing assembly 65 and shaft 66, rotates the turbofans 50 within thehousing. To this end, the shaft 67 is drivably connected to a primemover 76 (see FIG. 1) through a drive train including a drive belt 78and a worm reducer 80 connected directly to the end of the shaft 67.Individual control of the rate of rotation of the turbofans 50 and thetrays 56 is therefore possible.

The shafts 66 and 67 are suitably joumaled at their upper ends in abearing support 84, while the shaft 67 at its lower end extends throughthe thrust bearing assembly 65. High temperature beatings can beconveniently used for this purpose, although the insulation structureand cooling air flow feature of the dryer obviates the need forelaborate cooling system for the bearings.

As the trays 56 revolve, the material carried by each tray istransferred to the next lowest tray. In this fashion the material isprogressively advanced through the dryer to a material dischargeassembly 86 in the bottom of the dryer housing 20, through which it isdischarged, as indicated by the arrows in FIG. 3B, to a carryoffconveyor or the like (not shown). The manner in which the material ispassed from tray to tray within the dryer will be readily understood byreferring to FIG. 1 1, where an expanded, planar representation of thevertical stack of trays 56 is depicted.

After the material is delivered through the inlet assembly 54, to fallon the upper tray 56a as it rotates beneath the assembly 54, it remainson the tray 56a for approximately one revolution of the tray. The trayis illustrated in FIG. 1 1 as rotating in the counterclockwisedirection. It is then wiped over the outer edge of the tray, as will bemore fully described hereinafter, and

tray and into the nextlower transfer chute 88b to be delivered to thelower tray 56c. This process is repeated until the material has beendischarged from the dryer through the discharge assembly 86.

That is to say, the material remains on each tray for approximately onerevolution of the tray and is then diverted into the upper end of theassociated transfer chute 88 to be directed onto the next lower tray. Inorder that this process of successively passing the material from tray,to tray upon each revolution of the trays can be carried out, it isimportant that material transfer chute 88 for receiving material carriedby a tray be positioned properly in relation to the position of thetransfer chute 88 delivering the material to that particular tray. Forexample, in FIG. 11, the material transfer chute 880 must be located ina direction clockwise from the lower end of the material inlet means 54,since, as noted, the trays rotate in the counterclockwise direction, sothat the material will be carried by the tray 56a for approximately afull revolution before reaching the position of the chute 880.Similarly, the transfer chutes 88b to 88g must be positioned clockwiseof the correspondingly higher transfer chutes 88a to 88f. With thetransfer chutes 88 thus arranged, the material will be delivered to thetrays 56b to 56h at the correct circumferential position to be retainedon the respective trays for nearly a full revolution of the trays. Ofcourse, the length of time the material remains on any one tray can becontrolled by regulating the speed of rotation of the trays.

It is an important feature of the invention that the material isdelivered to the upper tray 56a and is thereafter transferred betweentrays along a path that is inclined at least over a portion of itslength, thereby minimizing billowing of the material and hence retardingthe formation of dust within the dryer. In FIGS. 3A,

4 and 5, the structure of the material inlet assembly 54 into a materialtransfer chute 88a which extends by which the material is admittedthrough the upper wall assembly 30 and delivered to the upper tray 56aincludes an insert member 90 that is received within an opening providedin the upper wall assembly 30 and rests on a peripheral flange 92extending around the upper end of the opening. A plurality of clips 94are attached to the lower side of the wall assembly 30 and areadapted'to receive in sliding relation the flanged upper ends of aninclined chute 96, which is of a width approximating the lateral widthof the annular tray 56a. Material passing through the insert 90 isdeflected along an inclined path by the side wall 98 (see FIG. 4) of thechute 96 and is delivered in a gentle manner onto the surface of thetray 56a as it rotates beneath the lower end of the chute. Feeding ofthe material to the dryer thus results in minimum breakage, minimumformation of fines and minimum adhesion of the material to the inletassembly. The laterally outer wall of the chute 96 is extended in thedirection of rotation of the tray 56a to form a baffle-like member 100for preventing the material from flowing over the outer edge of thetray.

Similarly, the material transfer chutes 88 are constructed to transferthe material between trays along an inclined path, thereby furtherretarding dust creation and minimizing breakage of the material andadhesion of the material to the transfer chutes. For example, in FIGS.3B and 7, the transfer chute 88g extending cludes an inclined centralportion 102g onto which the material falls, as indicated by the arrowsin FIG. 3B, upon being wiped off the surface of the tray 56g. Anotherimportant feature of the transfer chute construction, is that theinclined portion 102g does not extend to the surface of the tray 56h,but terminates well above the tray surface at the upper end of avertically extending portion 104g of the chute that defines an outerboundary for the material and confines it to the surface of the tray56h.

The foregoing configuration of the transfer chutes 88 Accordingly, asthe tray 56g rotates beneath the wiper arms 116g and 118g, the-materialis pushed by the wiper arms off the outer edge of the tray and is ispreferred inasmuch as it has been discovered that if the inclinedportions 102 extend over the full distance between adjacent trays theopenings between the outer edge of the trays and the adjacent surfacesof the transfer chutes tend to clog. Attempts to avoid such clogging byspacing the upper ends of the inclined portions 102 farther from theouter edges of the trays have proved unsatisfactory since this requiresthat the heating zone within the housing be undesirably enlarged. On theother hand, if the portions 102 are more steeply inclined, poordistribution of the material on the lower tray surface results.

In a preferred embodiment of the transfer chutes, again using the chute88g as an example, an upper vertical portion 106g and side walls 108gare provided on the chute 88g more fully to confine the material as itmoves between trays. Each of the transfer chutes 88 is supported withinthe housing 20 by metal straps 110 and 112 (see FIG. 6) that are bolted,for example, to the side walls 108g of the transfer chute 88g. Thestraps 110 and 112 are in turn bolted to vertically extending plates 114 secured to the support columns 22.

Turning now to the manner in which the material is diverted from thetray surfaces and into the upper ends of the transfer chutes 88, FIG. 6illustrates a pair of wiper arms 116g and 118g extending in close,spaced relation to the surface of the tray 56g for guiding the materialoff the tray and into the transfer chute 88g. It will be understood, ofcourse, that a similar pair of wiper arms 116 and 118 are associatedwith each tray 56 in the dryer.

Preferably, the wiper arm 116g is supported by a strap .120 (see FIG.6), also bolted to a vertical plate 1 14, so as to extend from a pointnear the far end, relative to the direction of rotation of the trays, ofthe transfer chute 88g and across the surface of the tray 56g in a planegenerally tangential to the inner circumference of the tray to terminateat a point approximately on the inner edge of the tray. The wiper arm118g, on the other hand, is mounted so that its leading end isapproximately equidistant between the inner and outer edges of the tray56g and to extend approximately parallel to the arm 1 16g. A generallyL-shaped divider member 122g is positioned between the trays 56g and56h, for a purpose hereinafter described, and has bolted to the upperend of its vertical leg 124g the rearward end of the wiper arm 118g. Thehorizontal leg 126g is disposed at approximately a right angle to thevertical leg 124g and extends between the trays 56g and 56h toapproximately the midpoint of the trays (see FIG. 6). The vertical andhorizontal legs of the L- shaped member 122g are joined by a centerportion 128g which is inclined to conform with the inclined portion 102gof the material transfer chute 88g.

deflected by the inclined chute portion 102g onto the next lowest tray56h. However, because the vertical leg 124g and the central inclinedportion 128g of the divider member 122g in effect divide the transferchute 88g into two separate material flow channels (see FIG. 7), thematerial diverted to the transfer chute by the wiper arm 1 16g isdeposited on the tray 56h on one side of the horizontal leg 126g of thedivider member while the material diverted by the wiper-arm 1 18g isretained on the other side of the horizontal leg.

By this wiper arm and divider member arrangement not only is thematerial handled in a very delicate manner, but the position occupied onthe tray by the material is interchanged each time the material istransferred to a lower tray. This is clear from FIG. 6, where the arrowsindicate that the material moved off the tray 56g by the wiper arm 116g,i.e., the material occupying the inner half of the upper tray 56g, isdelivered by the transfer chute 88g and divider member 122g to the outerhalf of the next lowest tray 56h. Conversely, the material occupying theouter half of the upper tray is diverted by the wiper arm 118g, transferchute 88g and divider member 122g to the inner half of the lower tray56h. An important advantage is thus realized inasmuch as thorough mixingof the material is achieved, with the result that new moist surfaces arecontinuously being exposed to the drying atmosphere to enhance productquality and unifomrity and to increase drying efiicien- A baffle 130g isdisposed along the outer edge of the tray 56g immediately in advance ofthe leading end of the transfer chute 88g to prevent loss of thematerial over the outer edge of the tray. Appropriate angle ironsupports 132g and 134g are provided to hold the baffle 130g in theproper position. Since the area between the wiper arm 118g and thebaffle 130g converges as the chute 88g is approached, the baffle 130gpreferably is tapered upwardly in the direction of rotation of the trayto provide a boundary of increased height (see FIG. 7). If desired, asupport 136g may be attached between the baffle 130g and the wiper arm118g to stiffen the leading end of the wiper arm.

Upon being delivered to the lower tray 56h, and being guided to therespective portions of the tray by the divider member. 122g, thematerial is distributed evenly over the tray surface to a predeterminedlevel by an elongate leveler arm 138g. The leveler arm is bolted (seeFIG. 6) to the far side wall 108g of the transfer chute 88g and extendstherefrom over the tray surface, first in a vertically lengthenedportion 140 (see FIG. 7), that acts as a wiper arm to deflect thematerial discharged from the chute 88g on to the tray 56h, and,

with all other trays in the dryer, except as otherwise noted.

After one revolution of the tray 56h, the last tray in the dryer, thematerial is pushed over the edge of the tray by the wiper arms (notshown) associated with the tray 56h and falls on to the bottom wall ofthe housing 20, where it is pushed upon continued rotation of the traysby one or more blades 144 (see FIG. 3B) suspended from the tray supportstructure to the discharge outlet assembly 86. The blades 144 preferablyare mounted to permit adjustment of the clearance between the blades andthe bottom of the housing. Any suitable arrangement, such as the boltand elongate slot structure 146 illustrated in FIG. 313, can be used forthis purpose. Desirably, the blades 144 extend substantially beyond theouter edges of the trays 56 so that all of the material falling from thelower tray 56h will be swept along by the blades and discharged from thedryer.

The discharge assembly 86 includes a chute 148 of which the sides sloperelatively steeply toward the exhaust end of the chute to ensure thatadhesion of the material to the discharge assembly is kept to a minimum.At the material receiving end, the chute 148 is of a transverse widthsubstantially coextensive with the bottom wall of the housing;therefore, it readily receives the material delivered to the bottom wallfrom the tray 56h. An appropriate carryoff conveyor (not shown), or thelike, may be positioned beneath the chute 148 to remove the driedproduct for packaging or further processing. Alternatively, a vaporlock, for example, a high temperature rotary vapor lock apparatus, maybe connected between the chute 148 and whatever material handlingapparatus is used to carry the material away from the dryer to reducethe loss of heat, drying medium or solvent, as the case may be,

across the discharge assembly 86.

Another important feature 'of the dryer of the present invention is thatit is constructed to permit continuous uninterrupted operation at highlyelevated temperatures, for example, temperatures in the range of 1,100E, without damage being caused to the dryer skeletal or housingstructure by thermal expansion or contraction of the components thereofand without warping or jamming of the moving elements of the dryer. Partof this construction includes fully insulating the dryer housing 20 onthe side and end walls to reduce heat losses and to maintain as uniformas possible the temperature at the center and periphery of the dryingzone, thus improving product uniformity and reducing the magnitude ofthermal stresses created in the housing and tray structure.

The side panel units 28, therefore, take a sandwichlike configuration incross section, including two spaced metal sheets 150 and 152 and afiller of insulating material (see FIG. 3A and 3B). Preferably, twotypes of insulating material are used, a layer 154 of dense material,such as asbestos board or the like, abutting the outer surface of theinner sheet 152, and a looser layer 156, such as a wire-mesh fiberglassblanket, filling the space between the layer 154 and the outer sheet150. The sheets 150 and 152 are secured together at their upper andlower ends by generally Z- shaped end members 158 and 160, respectively,which are in turn bolted to flanged support elements 162 and 164 carriedby the skeletal structure of the dryer. Similarly, the sheets 150 and152 are attached along the sides by Z-shaped members 163 (see FIG. 6),thereby forming a complete, enclosed insulating panel unit. Atconvenient locations around the periphery of the housing 20, one or moregas-tight sight ports 165 (see FIGS. 1 and 3A) may be provided in thepanels 28 The beams 166 are welded or otherwise secured togetherat theirheels, and to the opposite ends of the plate 168 at the outer ends oftheir adjacent legs, to en close with the plate 168 a generallytriangular area. Desirably, the legs of the beams 166 attached to theplate 168 are arranged at an angle relative to each other such that thepanel units 28 are received betweenv the facing beams 166 of adjacentcolumns 22 atapproximately right angles. v

Associated with each column 22 is a channel member 170 (see FIG. 6), thelegs of which are aligned with the outer legs of the respective L-shapedbeams 166 so as to face the side members 163 of the panel units 28. Thechannel member 170 also has facing flanges 172 at the outer ends of itslegs, to which are bolted the ends of the members 163 and outer sheetsof the adjacent panel units 28. Accordingly, each panel unit 28 isfirmly attached at either side, through the channel members 170, to theadjoining panel units 28, but not so fimily as to prevent expansion andcontraction of the housing 20. In fact, the configuration of the channelmembers 170, by which the panel units 28 are connected to the flanges172 at the outer ends of flexible legs, facilitates lateral inward oroutward movement of the housing walls by allowing limited movement ofthe panels along the circumference of the housing.

To avoid large temperature drops across the housing walls at thelocation of the columns 22 and to preserve the integrity of theinsulation shield, insulation members 174, preferably of asbestosmaterial, are placed within the channel members and are held in positiontherein by elongate metal sheets 176. Additional rigidity may be addedto the housing 20, if desired, by tieing adjacent panel units 28together with metal straps 178 and 180 (see FIGS. 3A and 3B) located atthe upper and lower ends, respectively, of the panels.

The insulation provided in the lower wall assembly 32, as illustrated inFIGS. 38, may consist substantially of asbestos material 182. Thismaterial is contained within a sheet metal enclosure formed by annular,generally L-shaped members 184 underlying the area between the cage 58and the side walls of the housing and a plurality of end sections 186,corresponding in number to the number of panel units 28, that arebolted, as at 188, to the outer end of the L-shaped members 184. The endsections 186 are supported (see FIG. 8) by the channel members 170 insubstantially the same way as the panel units 28, and are furtherconnected at their inner walls 189 to an L-shaped, annular girth member190 carried by the columns 22 in encircling relation of the lower end ofthe dryer.

That portion of the ,lower end of the dryer located within the cage 58is insulated by an annular pad 192 (see FIG. 3B) of asbestos materialenclosed within a sheet metal enclosure 194 and mounted on the cageassembly frame structure 64 for rotation therewith. The pad 192 overlapsthe inner end of the insulating material 182 to provide a continuity ofinsulation material across the lower end of the dryer. Apertures areformed in the pad 192 and enclosure 194 for passage of the stanchions 60of the cage assembly 58.

The upper wall assembly 30 (see FIG. 3A) has the same basicsandwichstructure as the panel units 28, but differs therefrom in thatthe upper sheet 196 of the assembly, referred to herein for purposes ofillustration as the cold roof, is attached, by welding, for example, tothe upper support frame 26 and the lower sheet 198, referred to hereinas the "hot roof, together with the overlying layers 200 and 202 ofasbestos and fiberglass materials, is carried by the cold roof 196 so asto be movable relative thereto. This is accomplished by suspending thehot roof 198 from the cold roof 196 through-the use of a plurality ofpairs of mating, U- shaped brackets 204 and 206 attached to the coldroof 196 and hot roof 198, respectively (see FIGS. 2 and 3A). As the hotroof 198 is supported solely by the brackets 204 and 206, it is free toexpand or contract laterally of the housing in response to variations ofthe temperature within the housing. If desired, the hot roof 198 may betied to an upper girth member 208, which may also carry the elements 162for supporting the panels 28.

To prevent wrinkling of the cold roof 196 caused by the leakage of hotair currents along its lower surface, a gasket 207 (see FIGS. 2 and 3A)is lapped over the end of the hot roof and is held tightly against afacing flange 209 on the cold roof by an L-shaped clamp 211 bolted tothe cold roof. As is apparentfrom FIG. 2, the gasket 207 and clamp 209extend along the entire periphery of the hot roof.

' The upper wall assembly 30 is dimensioned to overlap the upper ends ofthe panel units 28 (see FIG. 3A), thus fully sealing off the drying zonefrom the environment. Moreover, as the cold roof 196 and the uppersupport frame 26 are shielded from the high temperatures within thedryer housing, it is possible to position accurately the shafts 66 and67, the heating elements 42 and the associated fuel intake and exhaustequipment, in relation to the interior of the dryer housing 20,

v as well as in relation to the accessory equipment servicing the dryer,and to preserve the alignment of these elements during operation of thedryer. Also, access to the equipment carried by the frame 26 is possibleat all times. This is important should it develop that adjustments orrepairs need be made to the equipment during drying operations.

To ensure that the hot roof 198 is free to expand and contract withoutjamming against the heating elements 42 and the various other equipmentextending through the upper wall assembly 30, the openings provided inthe hot roof are oversized and offset from the corresponding openings inthe cold roof 196 to an extent that the hot roof 198 can expand the fulldistance anticipated at the highest operating temperature of the dryerwithout engaging this equipment. For example, in FIG. 3A, the opening210 formed in the hot roof 198 to admit the material inlet assembly 54is significantly larger in size than the corresponding opening in thecold roof 196, i.e., the opening surrounded by the peripheral flange 92.Likewise, the openings 214 (see FIG. 2) for the heating elements 42 arealso enlarged to allow for expansion of the hot roof.

As mentioned, provision is made for permitting expansion and contractionof the dryer housing and its supportstructure. In a preferredembodiment, such provision includes load-transmitting expansion joints216 (see FIG. 1) located between the lower and upper ends of the supportcolumns 22 and the lower and upper support frames 24 and 26,respectively. All of the expansion joints are identical; therefore, onlyone will be described, it being understood that the description willapply to equally.

In FIG. 3A, a typical expansion joint 216 includes a pair of spacedplates 218 and 220 to which are attached, respectively, asleeve 222 anda pair of spaced upstanding ears 224, the sleeve 222 being receivedbetween the ears 224 and in turn receiving, in sliding engagement, a pin226 carried between the ears 224. A set screw 228 may be provided toanchor the pin 226 in fixed position relative to the ears 224.Desirably, the expansion joints 216 are interposed between and bolted tocooperating plates 230 and 232 secured to the ends of the columns 22 andthe support frames 24 and 26 (see FIGS. 3A and 38), although theselatter plates may be omitted if desired.

Preferably the sleeve 222 andpin 226 of each joint 216 are arranged inalignment with a radius of the housing to facilitate lateral movement ofthe columns 22 as the various dryer elements connected to the columnsexpand or contract during operation of the dryer. Accordingly, each ofthe expansion joints 216 associated with any one colurrm 22 are givenorientations such that both are aligned along the same radius of thehousing (see FIG. 1).

Provision is also made for expansion and contraction of the trays 56 andthe bottom wall of the housing to permit high temperature operation ofthe dryer and to make possible the maintenance of highly elevatedtemperatures in the upper portions of the dryer while using the lowertrays for cooling of the material before discharge. Turning first to thetray structure and referring to FIGS. 3B and 6, where the trays 56g and56h and the support structure therefore are representative of apreferred embodiment, the annular trays 56g and 56h are formed of aplurality of truncated segements 234 supported in a generally horizontalplane in end to end relation on a pair of laterally spaced, L-shapedannular rings 236 and 238. At each vertical position along thestanchions 60 at which a tray 56 is to be located, L- shaped arms 240are mounted thereon to extend radially from the stanchions 60 and to beattached at their outer ends-to the vertically depending leg of theouter ring 238. To allow for movement of the ring 238, this attachmenttakes the form of a slidable joint constituted by L-shaped brackets 241(see FIGS. 3B and 6) that are secured to the arms 240 by a bolt andelongate slot arrangement 243. v

The inner annular ring 236 is also supported by the radial arms 240, butinstead of being secured directly to the arms, as is the outer ring 238,gaps 242 are formed in the ring (see FIG. 7) so that the ring 236 is infact a plurality of separate arcuate segments 244 that arecircumferentially spaced at their ends a distance sufficient to allowthe arms 240 to pass between'adjacent segments. An annular metal band246 is attached to the upper portion of the vertically extending legs ofthe segments 244 and is notched at 248 (see FIG. 7) at radial positionscorresponding to the positions of the arms 240 so that the band 246 fitsover the arms 240 and rests against the upper horizontal leg of the armsin a manner such that the horizontal upper legs of the segments 244 arein approximately the same plane as the horizontal upper legs of the arms240 and the horizontal upper leg of the-outer ring 238. The ring 236 isposi- Also, the band 246 serves to keep the material carried by thetrays from falling over the inner edges of the trays. Each tray segment234 is mounted on the inner ring 236 and the outer ring 238 of the traysupport structure in a manner to permit both circumferential and radialexpansion and contraction of the segments. Thus in FIGS. 3B, 6 and 7,the tray segments 234 are welded, or otherwise secured, at one end tothe horizontal leg of an L-shaped bracket 250, the vertical leg of whichis bolted to the vertical leg of the arm 240. Elongate slots 252 in thebracket 250 allow relative movement between the bracket 250 and thesupporting arm 240 due to different rates of expansion or contraction ofthe bracket, or tray segments 234, and the arms 240.

At the other end, and along the inner and outer edges, the tray segments234 are slidably clamped to the horizontal legs of the adjacent arms 240and to the inner ring segments 244 and the outer ring 238, respectively.In FIG. 6, the arrangement of the clamps 254 and the annular rings 236and 238 and arms 240 by which thermal expansion and contraction of thetray segments 234 is possible is clearly shown. There, the clamps 254that coact with the horizontal legs of the inner ring segments 244 andthe outer ring 238 are spaced along the respective edges of the traysegments 234 and are disposed to open in the radially inward directionso as to slip over the outwardly oriented (see FIG. 7) horizontal legsof the rings. Also, the clamps 254 coacting with the horizontal legs ofthe arms 240 are located to open toward the end of the segments 234 andto slip over the facing legs of the arms 240. The individual traysegments 234 are therefore easily installed on or removed from the traysupport structure simply by sliding them inwardly and circumferentiallyto engage the clamps 254 with the respective horizontal legs of theinner and outer rings 236 and 238 and the radial arms 240. Thereafter,the bolts securing the bracket 250 to the vertical leg of the adjacentarm 240 are tightened sufficiently to hold the tray segment in place,but not so tightly as to preclude expansion or contraction of thesegment relative to the arm.

The bottom wall of the dryer is similarly constructed to allow forthermally induced changes in dimension and is further designed tofacilitate fabrication of the dryer. In FIGS. 8, 9 and 10, the bottomwall of the 1 dryer is formed by multiple arcuate segments 256 suptachedto the dryer skeletal structure. Preferably, the

ring 258 is arranged so that its vertical leg extends upwardly to form aboundary against leakage of the material off the inner edges of thebottom wall. A similar function is performed at the outer edge of thebottom wall by the inner walls-189 of the end sections 186 of the-lowerwall assembly 32.

Each bottom wall segment 256 is attached at one circumferential end (seeFIG. 10) to the horizontal leg of a bracket 266, the bracket 266 beingbolted to the vertical leg of the adjacent arm 260. At the other end,the segment carries on its undersurface a plurality of L- shaped clampelements 268 for gripping the am 260. Similar clamp elements 268 arealso positioned along the radially inner and outer edges of the wallsegments to cooperate with the horizontal legs of the ring 258 and thegirth 190, respectively (see FIG. 9).

The clamp elements 268 include a fixed L-shaped bracket 270 and anassociated movable element 272. The movable element 272 are adjustablevertically, as by a bolt and elongate slot arrangement 274, so as to beabutted against the horizontal legs of the respective support members.With this arrangement, the lower wall of the dryer is readily assembledin that the segments 256 may be dropped in position on the ring 258 andgirth member and thereafter easily secured to the horizontal legs ofthese members and also to the horizontal leg of the adjacent radial arm260. The bracket 266 may then be bolted to the vertical leg of the arm260 to fix the segment 256 in position. However, since the segments 256are fixedly attached to only one arm 260, they are free to expand orcontract in either the radial or circumferential direction. Accordingly,high drying temperatures can be maintained through the vertical extendof the dryer and across the bottom wall, without causing warping orbuckling of the bottom wall or without causing misalignment of thedischarge assembly 86.

The tray segments 234 and bottom wall segments 256, as well as otherparts of the dryer in contact with the material being dried, may beconstructed of steel or any special alloy. They may also be of corosionresistant and cost saving materials such as enameled steel, asbestoscement board or glass fiber laminates.

During operation a slight negative pressure is preferably maintainedwithin the dryer housing 20 so that at any point on the housing whereleakage of the drying medium or airborne particles might be expected aninwardly flow of air will exist. Also, it is an important feature of theinvention that an inward, pressurized flow of air is maintained alongthe shafts 66 and 67 at the points where they extend through the dryerhousing. Thus, an air line 276 associated with the thrust bearingassembly.65 delivers air'under pressure-to the interior of the assemblyto cool it and to prevent leakage of dust along the shaft (see thearrows in FIG. 38). Similarly, there is av downward flow of air underpressure through the opening 278 in the upper wall assembly (see thearrows in FIG. 3A), the air being admitted through the air line 280,with additional air flowing through openings 282 in the bearing support84 and downward between the concentric shafts 66 and 67. -It will beappreciated, therefore, that the bearings for both of the shafts 66 and67 are cooled by these air flows and thatleakage along either shaft isprevented. Furthermore, the use of the leakage-preventing air flow tocool the bearings in the manner described precludes the need forelaborate cooling systems for the bearings or the use of expensive hightemperature bearings materials. I j v it will be apparent from theforegoing, that the continuous rotary dryer of the present invention .isespecially adapted for a wide variety of applications; whether fordrying alone; drying and cooling together; drying with solvent recovery;drying in a superheated vapor atmosphere, for example, where steam isused as the drying medium; for purifying solids by sublimation; forreacting gases with solid material carried by the trays; and for coolingalone. Moreover, the dryer finds particular application where fragileand normally dusty materials are to be processed and where breakage anddust levels generated during the handling of these materials are toominimized.

It will further be apparent to those skilled in the art that the abovedescribed embodiments are intended to be merely exemplary, in that theyare susceptible of modification and variation without departing from thespirit of the invention.

We claim:

1. In rotary dryer apparatus having a vertically extending housing inwhich a plurality of vertical support members are spaced around theperiphery of the housing, material inlet means adjacent the upper end ofthe housing, material outlet means adjacent the lower end of the housingand a plurality of vertically superimposed trays for carrying materialfrom the inlet means to the outlet means and mounted for rotation abouta generally vertical axis, the improvement comprising:

thermal insulation means extending peripherally around the housing andincluding portions exterior to the vertical support members to maintainthe temperature'of the support members approximately equal to that ofthe interior of the housing,

an upper, cold roof located across the upper end of the housing andsupported by the vertical support receiving, the pin member, the pinmember and sleeve member being disposed to allow relative movementtherebetween along a radius extending from the axis of rotation of thetrays, the other of the sleeve member and pin member being carried bythe cold roof in fixed relation to the said one pin member and sleevemember, whereby the vertical support members are laterally movable alongradii of the housing.

3. Apparatus according to claim 1 further compristhe trays within thehousing,

means located exteriorly of and spaced from the housing for journalingthe shaft means adjacent the upper and lower ends thereof, and

means associated with the journaling means for producing a flow of airinwardly along the shaft means to cool the shaft means and to preventleakage of the material along the shaft means.

4. Rotary dryer apparatus having a vertically extending housing, aninlet for receiving material adjacent the upper end of the housing, anoutlet for discharging material adjacent the lower end of the housing,and at least one annular tray, for carrying material from the inlet tothe outlet, mounted for rotation within the housing about a generallyvertical axis, wherein the improvement in the tray comprises:

a multiplicity of truncated segments arranged in endto-end relationabout the axis of rotation to define an annular, generally horizontalsurface,

an annular ring member supporting the radially inner edge of each of thesegments, the annular ring member resting on and being freely supportedby a plurality of circumferentially spaced, radially extending arms,

a second annular ring member secured to the radially outer ends of theradially extending arms, and

clamp meansv carried by the tray segments for slidably engaging theannular ring members and the radial arms to hold the segments in'position thereon while allowing circumferential and radial expansion orcontraction of the segments in I response to temperature changes withinthe dryer.

5. Rotary dryer apparatus including a vertically extending housinghaving an enclosed lower end, an inlet for material adjacent the upperend of the housing, an outlet for material adjacent the lower end of thehousing, and a plurality of vertically superimposed annular trays, forcarrying the material from the inlet to the outlet, mounted for rotationwithin the housing about a generally vertical axis, wherein theimprovement in the bottom wall of the housing comprises:

a multiplicity of truncated segments arranged in endto-end relationabout the axis of rotation to define an annular, generally horizontalsurface,

a plurality of radially extending arms underlying and supporting thesegments,

an annular ring member secured to the radially outer ends of the armsand supporting the radially outer edges of the segments, and

clamp means carried by the segments for slidably engaging the radialarms and annular ring member for holding the segments in positionthereon while allowing radial and circumferential expansion orcontraction of the segments caused by temperature variations.

vertically extending shaft means rotatably supporting 6. In rotary dryerapparatus having a vertically extending housing in which a plurality ofvertical support members are spaced around the periphery of the housing,material inlet means adjacent the upper end of the housing, materialoutlet means adjacent the lower end of the housing and a plurality ofvertically superimposed trays for carrying material from the inlet meansto the outlet means and mounted for rotation within the housing about agenerally vertical axis, the improvement comprising:

expansion joint means adjacent the upper and lower ends of the verticalsupport members for allowing lateral movement of the support members inresponse to thermally induced expansion or contraction of the housing,which expansion joint means includes a pin member disposed along aradius extending from the vertical axis of rotation of the trays and asleeve member slidably receiving the pin member, one of the pin memberand sleeve member being supported in fixed relation to the verticalsupport member and the other of the pin member and the sleeve memberbeing carried by the vertical support member and movable therewith alongthe said radius of the housing.

7. In rotary dryer apparatus having a vertically extending housing inwhich a plurality of vertical support members are spaced around theperiphery of the housing, material inlet means adjacent the upper end ofthe housing, material outlet means adjacent the lower end of the housingand a plurality of vertically superimposed trays for carrying materialfrom the inlet means to the outlet means and mounted for rotation withinthe housing about a generally vertical axis, the improvement comprising:

expansion joint means adjacent the upper and lower ends of the verticalsupport members for allowing lateral movement of the support members inresponse to thermally induced expansion or contraction of the housing;and

means associated with each tray for allowing expansion and contractionthereof, including an annular ring member for supporting the radiallyinner ends of the tray, the annular ring member resting on and beingfreely supported by a plurality of circum ferentially spaced, radiallyextending arms, a second annular ring member secured to the outer endsof the radially extending support arms, and clamp means carried by thetray for slidably engaging the annular ring members and the radial armsto hold the tray in position thereon while allowing circumferential andradial expansion of the tray in response to temperature changes thehousmeans associated with the journaling means for producing a flow ofair inwardly along the shaft means to cool the shaft means and toprevent leakage of the material along the shaft means.

l0. Rotary dryer apparatus comprising:

a vertically extendinghousinghaving material inlet means adjacent theupper end thereof and material outlet means adjacent the lower endthereof;

a plurality of vertically extending support members spaced around theperiphery of the housing;

a plurality of vertically superimposed trays for carrying materialbetween the inlet means and the outlet means and mounted for rotationwithin the housing about a generally vertical axis;

expansion joint means adjacent the upper and lower ends of the verticalsupport members including a pin member disposed along a radius extendingfrom the vertical axis of rotation of the trays and a sleeve memberslidably receiving the pin member, one of the-pin member and sleevemember being supported in fixed relation to the vertical support memberand the other of the pin member and the sleeve member being carried bythe vertical support member and movable therewith along the said radiusof the housing; and

thermal insulation means extending peripherally around the housing andincluding portions exterior to the vertical support members to maintainthe temperature of the support members approximately equal to that ofthe interior of the housing.

1 1. Rotary dryer apparatus comprising:

a vertically extending housing having material inlet means adjacent theupper end thereof and material outlet means adjacent the lower endthereof;

a plurality of vertically extending support members spaced around theperiphery of the housing;

a plurality of vertically superimposed trays for carrying materialbetween the inlet means and the outlet means and mounted for rotationwithin the housing about a generally vertical axis;

means adjacent the upper and lower ends of the vertical support membersfor allowing lateral movement of the support members in response tothermally induced expansion or contraction of the housing; and

means for thermally insulating the housing including panel membersextending peripherally between adjacent vertical support members and anindividual insulator member disposed exteriorly of each of the verticalsupport members for insulating the respective support members.

12. Rotary dryer apparatus comprising:

a vertically extending housing having material inlet means adjacent theupper end thereof and material outlet means adjacent the lower endthereof;

a plurality of vertically extending support members spaced around theperiphery of the housing;

a plurality of vertically superimposed trays for carrying materialbetween the inlet means and the outlet means and mounted for rotationwithin the housing about a generally vertical axis;

means adjacent the upper and lower ends of the vertical support membersfor allowing lateral movement of the support members in response tothermally induced expansion or contraction of the housing;

thermal insulation means extending peripherally around the housing andincluding portions exterior to the vertical support members to maintainthe temperature of the support members approximately equal to that ofthe interior of the housing;

'19 20 a laterally extending insulator wall assembly located meanscarried by the hot'and cold roofs for suspendacross the upper end of thehousing and in l di ing the hot roof from the cold roof in a mannerto anupper, cold roof and a lower, hot roof; allow lateral movement of thehot roof relative to insulating material disposed between the hot andthe cold Toofdue to thermal fl cold roofs; and i *zgz gy UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No; 3,681,861 DatedAugust 8 1912 Inventor(s) Eda d B Alexander M. Lane It is certified thaterror appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

.Column 3, line 52, from" should read --for--;

Column 14, line 17, "edges should read --edge--;

Column 1 line 33*, "element" should'be --elements--;

Signed and sealed this 6th day of March 1973.-

(SEAL) Attest:

EDWARD I 'I.FLETCHER,JR. ROBERT GOTTSCHALK Attesting OfficerCommissioner of Patents

1. In rotary dryer apparatus having a vertically extending housing in which a plurality of vertical support members are spaced around the periphery of the housing, material inlet means adjacent the upper end of the housing, material ouTlet means adjacent the lower end of the housing and a plurality of vertically superimposed trays for carrying material from the inlet means to the outlet means and mounted for rotation about a generally vertical axis, the improvement comprising: thermal insulation means extending peripherally around the housing and including portions exterior to the vertical support members to maintain the temperature of the support members approximately equal to that of the interior of the housing, an upper, cold roof located across the upper end of the housing and supported by the vertical support members, a lower, hot roof underlying the cold roof and extending across the upper end of the housing, heat insulation means located between the hot roof and the cold roof, and means carried by the cold roof for suspending the hot roof therefrom in a manner to allow expansion and contraction thereof relative to the cold roof in response to temperature changes within the housing.
 2. Apparatus according to claim 1 in which each of the vertical support members carries adjacent its upper end one of a pin member and a sleeve member slidably receiving the pin member, the pin member and sleeve member being disposed to allow relative movement therebetween along a radius extending from the axis of rotation of the trays, the other of the sleeve member and pin member being carried by the cold roof in fixed relation to the said one pin member and sleeve member, whereby the vertical support members are laterally movable along radii of the housing.
 3. Apparatus according to claim 1 further comprising: vertically extending shaft means rotatably supporting the trays within the housing, means located exteriorly of and spaced from the housing for journaling the shaft means adjacent the upper and lower ends thereof, and means associated with the journaling means for producing a flow of air inwardly along the shaft means to cool the shaft means and to prevent leakage of the material along the shaft means.
 4. Rotary dryer apparatus having a vertically extending housing, an inlet for receiving material adjacent the upper end of the housing, an outlet for discharging material adjacent the lower end of the housing, and at least one annular tray, for carrying material from the inlet to the outlet, mounted for rotation within the housing about a generally vertical axis, wherein the improvement in the tray comprises: a multiplicity of truncated segments arranged in end-to-end relation about the axis of rotation to define an annular, generally horizontal surface, an annular ring member supporting the radially inner edge of each of the segments, the annular ring member resting on and being freely supported by a plurality of circumferentially spaced, radially extending arms, a second annular ring member secured to the radially outer ends of the radially extending arms, and clamp means carried by the tray segments for slidably engaging the annular ring members and the radial arms to hold the segments in position thereon while allowing circumferential and radial expansion or contraction of the segments in response to temperature changes within the dryer.
 5. Rotary dryer apparatus including a vertically extending housing having an enclosed lower end, an inlet for material adjacent the upper end of the housing, an outlet for material adjacent the lower end of the housing, and a plurality of vertically superimposed annular trays, for carrying the material from the inlet to the outlet, mounted for rotation within the housing about a generally vertical axis, wherein the improvement in the bottom wall of the housing comprises: a multiplicity of truncated segments arranged in end-to-end relation about the axis of rotation to define an annular, generally horizontal surface, a plurality of radially extending arms underlying and supporting the segments, an annular ring member secured to the radially outer ends of the arms and supporting the radially oUter edges of the segments, and clamp means carried by the segments for slidably engaging the radial arms and annular ring member for holding the segments in position thereon while allowing radial and circumferential expansion or contraction of the segments caused by temperature variations.
 6. In rotary dryer apparatus having a vertically extending housing in which a plurality of vertical support members are spaced around the periphery of the housing, material inlet means adjacent the upper end of the housing, material outlet means adjacent the lower end of the housing and a plurality of vertically superimposed trays for carrying material from the inlet means to the outlet means and mounted for rotation within the housing about a generally vertical axis, the improvement comprising: expansion joint means adjacent the upper and lower ends of the vertical support members for allowing lateral movement of the support members in response to thermally induced expansion or contraction of the housing, which expansion joint means includes a pin member disposed along a radius extending from the vertical axis of rotation of the trays and a sleeve member slidably receiving the pin member, one of the pin member and sleeve member being supported in fixed relation to the vertical support member and the other of the pin member and the sleeve member being carried by the vertical support member and movable therewith along the said radius of the housing.
 7. In rotary dryer apparatus having a vertically extending housing in which a plurality of vertical support members are spaced around the periphery of the housing, material inlet means adjacent the upper end of the housing, material outlet means adjacent the lower end of the housing and a plurality of vertically superimposed trays for carrying material from the inlet means to the outlet means and mounted for rotation within the housing about a generally vertical axis, the improvement comprising: expansion joint means adjacent the upper and lower ends of the vertical support members for allowing lateral movement of the support members in response to thermally induced expansion or contraction of the housing; and means associated with each tray for allowing expansion and contraction thereof, including an annular ring member for supporting the radially inner ends of the tray, the annular ring member resting on and being freely supported by a plurality of circumferentially spaced, radially extending arms, a second annular ring member secured to the outer ends of the radially extending support arms, and clamp means carried by the tray for slidably engaging the annular ring members and the radial arms to hold the tray in position thereon while allowing circumferential and radial expansion of the tray in response to temperature changes within the housing.
 8. Apparatus according to claim 7 in which each tray is annular in plan and comprises a multiplicity of circumferentially arranged, truncated segments.
 9. Apparatus according to claim 7 further comprising: vertically extending shaft means rotatably supporting the trays within the housing, means located exteriorly of and spaced from the housing for journaling the shaft means adjacent the upper and lower ends thereof, and means associated with the journaling means for producing a flow of air inwardly along the shaft means to cool the shaft means and to prevent leakage of the material along the shaft means.
 10. Rotary dryer apparatus comprising: a vertically extending housing having material inlet means adjacent the upper end thereof and material outlet means adjacent the lower end thereof; a plurality of vertically extending support members spaced around the periphery of the housing; a plurality of vertically superimposed trays for carrying material between the inlet means and the outlet means and mounted for rotation within the housing about a generally vertical axis; expansion joint means adjacent the upper and lower ends of The vertical support members including a pin member disposed along a radius extending from the vertical axis of rotation of the trays and a sleeve member slidably receiving the pin member, one of the pin member and sleeve member being supported in fixed relation to the vertical support member and the other of the pin member and the sleeve member being carried by the vertical support member and movable therewith along the said radius of the housing; and thermal insulation means extending peripherally around the housing and including portions exterior to the vertical support members to maintain the temperature of the support members approximately equal to that of the interior of the housing.
 11. Rotary dryer apparatus comprising: a vertically extending housing having material inlet means adjacent the upper end thereof and material outlet means adjacent the lower end thereof; a plurality of vertically extending support members spaced around the periphery of the housing; a plurality of vertically superimposed trays for carrying material between the inlet means and the outlet means and mounted for rotation within the housing about a generally vertical axis; means adjacent the upper and lower ends of the vertical support members for allowing lateral movement of the support members in response to thermally induced expansion or contraction of the housing; and means for thermally insulating the housing including panel members extending peripherally between adjacent vertical support members and an individual insulator member disposed exteriorly of each of the vertical support members for insulating the respective support members.
 12. Rotary dryer apparatus comprising: a vertically extending housing having material inlet means adjacent the upper end thereof and material outlet means adjacent the lower end thereof; a plurality of vertically extending support members spaced around the periphery of the housing; a plurality of vertically superimposed trays for carrying material between the inlet means and the outlet means and mounted for rotation within the housing about a generally vertical axis; means adjacent the upper and lower ends of the vertical support members for allowing lateral movement of the support members in response to thermally induced expansion or contraction of the housing; thermal insulation means extending peripherally around the housing and including portions exterior to the vertical support members to maintain the temperature of the support members approximately equal to that of the interior of the housing; a laterally extending insulator wall assembly located across the upper end of the housing and including an upper, cold roof and a lower, hot roof; insulating material disposed between the hot and cold roofs; and means carried by the hot and cold roofs for suspending the hot roof from the cold roof in a manner to allow lateral movement of the hot roof relative to the cold roof due to thermal effects. 